Information about Sisal

SISAL

Paradigm:	functional, dataflow
Appeared in:	1983
Designed by:	James McGraw
Developer:	James McGraw et al, at University of Manchester, LLNL, Colorado State University, and DEC
Typing discipline:	static, strong
Major implementations:	osc, sisalc
Influenced by:	VAL, Pascal, C, Fortran

SISAL (Streams and Iteration in a Single Assignment Language) is a general-purpose single assignment functional programming language with strict semantics, implicit parallelism, and efficient array handling. SISAL outputs a dataflow graph in Intermediary Form 1 (IF1). It was derived from VAL (Value-oriented Algorithmic Language), and adds recursion and finite streams. It has a Pascal-like syntax and was designed to be a common high-level language for numerical programs on a variety of multiprocessors.

History

SISAL was defined in 1983 by James McGraw et al, at the University of Manchester, LLNL, Colorado State University and DEC. It was revised in 1985, and the first compiled implementation was made in 1986. Its performance is superior to C and rivals Fortran, combined with efficient and automatic parallelization.

SISAL's name came from grep'ing "sal" for "Single Assignment Language" from the Unix dictionary /usr/dict/words.

Versions exist for the Cray X-MP, Y-MP, 2; Sequent, Encore Alliant, dataflow architectures, Transputers and systolic arrays.

References

• VAL Overview
• Sisal Language Tutorial

External links

• SISAL Parallel Programming SourceForge.net project page

This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.

---

Sisal
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Liliopsida Order: Asparagales Family: Agavaceae Genus: Agave Species: A. sisalana
Binomial name
Agave sisalana Perrine

Sisal or sisal hemp is an agave Agave sisalana that yields a stiff fiber used in making rope. (The term may refer either to the plant or the fiber, depending on context.) It is not really a variety of hemp, but named so because hemp was for centuries a major source for fiber, so other fibers were sometimes named after it.

Sisal plants consist of a rosette of sword-shaped leaves about 1.5 to 2 meters tall. Young leaves may have a few minute teeth along their margins, but lose them as they mature. Sisals are sterile hybrids of uncertain origin; although shipped from the port of Sisal in Yucatán (thus the name), they do not actually grow in Yucatán, the plantations there cultivate henequen (Agave fourcroydes) instead. Evidence of an indigenous cottage industry in Chiapas suggests it as the original location, possibly as a cross of Agave angustifolia and Agave kewensis.

In the 19th century, sisal cultivation (the plant being propagated via offsets), was spread worldwide, from Florida to the Caribbean islands and Brazil, as well as to countries in Africa, notably Tanzania and Kenya, and Asia. Among flax, hemp, abaca, sunn hemp (Crotalaria juncea)^[1] and other agro-based fiber species, annual sisal production is the second largest worldwide, after cotton; refer to the statistical databases by FAO, the United Nations Organisation for Food and Agriculture (www.fao.org).

Sisal fibers are typed by properties relational to the performance of the fiber. Researcher Sara Kadolph has found that sisal fibers are smooth, straight and yellow and can be long or short. Since sisal is fairly coarse and inflexible, Kadolph finds that sisal is used by itself or in blends with wool and acrylic for a softer hand.^[2] Sisal is valued for cordage use because of its strength, durability, ability to stretch, affinity for certain dyestuffs, and resistance to deterioration in saltwater.^[3] Sisal is used by industry in three grades, according to www.sisal.ws. The lower grade fiber is processed by the paper industry because of its high content of cellulose and hemicelluloses. The medium grade fiber is used in the cordage industry for making: ropes, baler and binders twine. Ropes and twines are widely employed for marine, agricultural, and general industrial use. The higher-grade fiber after treatment is converted into yarns and used by the carpet industry.^[3]

Products made from sisal are being developed rapidly, such as furniture and wall tiles made of resonated sisal. A recent development expanded the range even to car parts for cabin interiors.^[3] Other products developed from sisal fiber include spa products, cat scratching posts, lumbar support belts, rugs, slippers, cloths and disc buffers. Sisal wall covering meets the abrasion and tearing resistance standards of the American Society for Testing and Materials and of the National Fire Protection Association.^[4] Traditionally, sisal has been the leading material for agricultural twine (“binder” and “baler” twine) but the importance of this is diminishing with competition from polypropylene and other techniques evolving.^[5] Apart from ropes, twines and general cordage sisal is used in low-cost and specialty paper, dartboards, buffing cloth, filters, geotextiles, mattresses, carpets, handicrafts, wire rope cores and macrame.^[5] In recent years sisal has been utilized as a strengthening agent to replace asbestos and fiberglass as well as an environmentally friendly component in the automobile industry.^[5] Products made from sisal fiber are purchased throughout the world and for use by the military, universities, churches and hospitals.^[4]

It may be to the consumer’s advantage to know the following characteristics of products made with sisal fiber, according to www.wigglesworthfibres.com. Despite the yarn durability sisal is known for, slight matting of carpeting may occur in high traffic areas[5]. Sisal does not build up static nor does it trap dust, so vacuuming is the only maintenance required. High spill areas should be treated with a fiber sealer and for spot removal, a dry cleaning powder is recommended. Depending on climatic conditions, sisal will absorb air humidity or release it causing expansion or contraction. Sisal is not recommended for areas that receive wet spills, or rain or snow.^[5]

The sisal plant has a 7-10 year life-span and typically produces 200-250 commercially usable leaves. Each leaf contains an average of around 1000 fibers. The fiber element, which accounts for only about 4% of the plant by weight, is extracted by a process known as decortication. In East Africa, the leaves are transported to a central decortication plant after which the fiber is dried, brushed and baled for export. In Brazil it is mainly grown by smallholders and the fiber is extracted by teams using portable raspadors. Superior quality sisal is found in East Africa, once washed and decorticated. Sisal is considered a plant of the tropics and subtropics, since production benefits from temperatures above 25 degrees Celsius and sunshine.^[5]

Sisal production reported in 2003 at www.wigglesworthfibres.com, notes that Tanzania produced approximately 22,000 tons per annum, 22,000 tons in Kenya and 8,000 tons in Madagascar. China contributed 40,000 tons with smaller amounts coming from South Africa, Mozambique, Haiti, Venezuela and Cuba. In Mexico henequen production has fallen from 160,000 tons in the 1960’s to about 15,000 tons today.^[5] The first commercial plantings in Brazil were not made until the late 1930’s and the first sisal fiber exports from there were made in 1948. It was not until the 1960‘s that Brazilian production really accelerated and the first of many spinning mills were established. Today Brazil is the major world producer of sisal at 125,000 tons[5]. Sisal occupies 6th place among fiber plants, representing 2% of the world’s production of plant fibers (plant fibers provide 65% of the world’s fibers).^[6]

Researchers reporting on www.nnfcc.co.uk have published fiber extraction information on sisal fiber. In the process of decortication, leaves are crushed and beaten by a rotating wheel set with blunt knives, so that only fibers remain. All other parts of the leaf are washed away by water. Decorticated fibers are washed before drying in the sun or by hot air. Proper drying is important as fiber quality depends largely on moisture content. Artificial drying has been found to result in generally better grades of fiber than sun drying. Dry fibers are machine combed and sorted into various grades, largely on the basis of the previous in-field separation of leaves into size groups.^[6]

According to www.advancedbuildings.org, sisal farming initially caused great environmental degradation, because sisal plantations replaced native forests, but is still considered less damaging than most. No pesticides or chemical fertilizers are used in sisal production, and although herbicides are occasionally used, even this impact may be eliminated, since most weeding is done by hand.^[4]

Heraldry

The "sisal tree" appears in the arms of Barquisimeto, Venezuela.^[7]

References

• G. W. Lock, Sisal (Longmans Green & Co., 1969)
• Howard Scott Gentry, Agaves of Continental North America (University of Arizona Press, 1982) pp. 628-631

•  • [ e] Fibers
Natural:	Alpaca Angora Asbestos Cashmere Catgut Coir Cotton Flax Hemp Jute Llama Mohair Pia Ramie Silk Sinew Sisal Spider silk Wool
Synthetic:	Acrylic Aramid (Kevlar, Nomex) Carbon fiber Microfiber Nylon Olefin Polyester Rayon Spandex